The aim of this study is to examine the relationships between net gastric emptying of liquid meals and electrical and motor activity of the antrum and duodenum. In previous studies examining various hormones and test solutions, we found that while all cause delay in emptying of meal, the effects on antral and duodenal motor activity varied markedly, often having opposite effects. This evidence suggested that the antrum was not the regulator of emptying of liquid meals. The proposed studies intend to carry this hypothesis further and examine the relationships between volume passing the polyrus/unit time and the force and frequency of antral contractions. This will be attempted using dogs with gastric and duodenal fistulas and chronically implanted strain gage transducers and electrodes. Various volumes ranging from 100 to 500 ml will be put into the stomach via the gastric fistula and collections made from the duodenal fistula at 1 minute intervals. This data will help provide information concerning the role of the antrum as a pump regulating gastric emptying. Collateral studies will also be attempted to examine the effect of experimental gastric and duodenal ulcers on the gastric emptying process. In these studies, after control experiments, a gastric or a duodenal ulcer will produced and then the emptying re- studied. Meals of saline, acid and glucose will be studied. It is hoped that these studies will determine whether an ulcer per se has an effect on emptying.